1. Field of the Invention
The present invention relates to disk drives and, particularly, to improved magneto-resistive asymmetry compensation for sampled amplitude read channels.
2. Description of the Related Art
Magnetic recording systems store information on a magnetic medium using regions of different magnetization. The magnetic transitions are read to and written by magnetic heads. It is desirable for the positive and negative pulses to have equal amplitudes. However, magneto-resistive heads can produce an asymmetric response signal. That is, the positive and negative peaks can have differing amplitudes. This can cause inaccuracies in readback.
As such, there is a need for magneto-resistive asymmetry compensation in magnetic recording systems employing magneto-resistive heads.
These and other drawbacks in the prior art are overcome in large part by a system and method according to the present invention. A magneto-resistive asymmetry compensation system includes a linearizer interposed in a data path and a control loop. The control loop uses signal estimates from an interpolated timing response unit to derive a magneto-resistive asymmetry error. The error term is used to obtain a control scaling input to the linearizer. The linearizer functions to multiply the scaling multiple to the square of the input signal and then to add it back to the input signal. A DC offset control loop may be also provided.
A better understanding of the invention is obtained when the following detailed description is considered in conjunction with the following drawings.